1. Field of the Invention
The present invention relates to a thin type electronic instrument such as electronic microcomputer and in particular to such electronic instrument which has a thickness in the order of from 0.5 to 2.0 mm and flexibility.
2. Description of the Prior Art
In making a thin and flexible microcomputer, man encounters some problems which the conventional microcomputer of rigid structure does not have. One of the problems concerns the mounting of the power switch. In most of the conventional rigid structures, the power switch was mounted on the side surface of the main body of the microcomputer. However, with the increasing tendency to minimization of the thickness of microcomputers it has become more and more difficult to mount the power switch on the side surface of the computer body. For a thin type microcomputer, therefore, the power switch must be provided on a surface coplanar to the keyboard surface.
As to the switching mechanism itself, there has been also a considerable change in recent years. Electronic power switches such as P1, P2 shown in FIGS. 5 and 6 of the accompanying drawing are rapidly replacing the conventional mechanical locking switch in the microcomputer art. In case of the power switches P1, P2, On-Off of a power source is effected by set-reset of an electronic flip-flop circuit. When such new type of power switch is employed, particular care should be taken to prevent the power source from being unintentionally switched on. Otherwise, the power of the cell may be consumed uselessly. This is true in particular when the microcomputer is made to have the same degree of flexibility as a credit card or cash card has, as in the cases of FIGS. 5 and 6. If a keyboard of the type having contacts made of electroconductive rubber or the like is used in the microcomputer, then the power switch P1 may be often turned On unintentionally and carelessly. This is very troublesome. Such trouble may be easily caused when a person carries it with him keeping it in his flexible pocketbook or card case.
Designing the keyboard is also a problem in making a thin and flexible microcomputer. Use of a conventional keyboard such as a two color molded plastics keyboard is undesirable because it is too thick and too expensive. A thin and relatively inexpensive keyboard can be obtained in a simple manner by printing characters and symbols on a thin keysheet constituting an even surface. But, the use of such keyboard has another drawback in that the printed characters and symbols are gradually rubbed off by repeated touching of fingers therewith and finally become unreadable.